The Belis planetary system excists of three planets. Belis Alta, Nova Belis and Belis Auris which all move around their single sun, Aurora. The Belis cluster itself was was right at the edge of the Segmentum Pacificus with Tanith being the closest planet.
The Sun Aurora had been burning bright and warm for thousands of years. When the belis sector was first discovered by the Imperial pioneer fleet of Admiral Avarell Prichard it was Aurora that had guided the fleet in like a beacon of light and hope in the vast darkness of empty space.